Treatment method

ABSTRACT

A method for treating cartilage of a human being includes, bringing an excision unit into contact with a predetermined portion of the cartilage, heating the predetermined portion of the cartilage to a temperature of 120° C. or higher by the excision unit within 2.2 seconds and excising, by the excision unit, the predetermined portion of the cartilage that has been heated to the temperature of 120° C. or higher while pressing the predetermined portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-part application of U.S. patentapplication Ser. No. 14/867,805 filed Sep. 28, 2015, and Ser. No.15/085,104 filed Mar. 30, 2016, the entire contents of both of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a treatment method.

2. Description of Related Art

Electrical surgical devices capable of treating cartilage are disclosedin Jpn. PCT National Publication No. 2007-519427, for example.

Specifically, the electrical surgical device disclosed in Jpn. PCTNational Publication No. 2007-519427 is capable of forming a smooth andstable cartilage surface by using radio frequency energy.

For treating cartilage, a device capable of excising a large amount ofcartilage in a short time to reduce the time for surgery is desired.Jpn. PCT National Publication No. 2007-519427 discloses a technique offorming the cartilage surface to be smooth.

BRIEF SUMMARY OF THE INVENTION

A method for treating cartilage according to an aspect of the inventioncomprises: bringing an excision unit into contact with a predeterminedportion of the cartilage; heating the predetermined portion of thecartilage to a temperature of 120° C. or higher by the excision unitwithin 2.2 seconds; and excising, by the excision unit, thepredetermined portion of the cartilage that has been heated to thetemperature of 120° C. or higher while pressing the predeterminedportion.

Advantages of the invention will be set forth in the description whichfollows, and in part will be obvious from the description, or may belearned by practice of the invention. The advantages of the inventionmay be realized and obtained by means of the instrumentalities andcombinations particularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 illustrates components of cartilage, cancellous bone, andcortical bone.

FIG. 2 illustrates the principle of cartilage excision by an ultrasonicsurgical system.

FIG. 3A illustrates the relationship between the amount of cartilageexcision and the temperature when a soldering iron is pressed ontocartilage with a predetermined pressure.

FIG. 3B illustrates the relationship between the amount of cartilageexcision and the temperature when an ultrasonic excision device ispressed onto cartilage with a predetermined pressure.

FIG. 4 illustrates a surface and a cross sectional view of cartilage foreach of the temperatures when the soldering iron is pressed ontocartilage.

FIG. 5A illustrates an increase of the temperature of a cartilage overtime when the ultrasonic excision device in which different outputs areapplied is pressed onto cartilage.

FIG. 5B illustrates an increase of the temperature of a subcartilaginousbone over time when the ultrasonic excision device is pressed ontocartilage with outputs A, B, and C of FIG. 5A.

FIG. 6A is a schematic diagram of temperature distribution of cartilage,subcartilaginous bone, and cancellous bone when the temperature of thecartilage is 120° C. at output A.

FIG. 6B is a schematic diagram of temperature distribution of cartilage,subcartilaginous bone, and cancellous bone when the temperature of thecartilage is 120° C. at output B.

FIG. 6C is a schematic diagram of temperature distribution of cartilage,subcartilaginous bone, and cancellous bone when the temperature of thecartilage is 120° C. at output C.

FIG. 7 illustrates an example of a detailed configuration of thesurgical system according to the embodiments of the present invention.

FIG. 8 is a block diagram showing a main configuration of the ultrasonicsurgical system according to the first embodiment of the presentinvention.

FIG. 9 is a graph showing the experimental results of measuring thechange in the amount of excision when a pressure or an amplituderelative to cartilage is changed.

FIG. 10 is a flowchart illustrating the treatment using the ultrasonicsurgical system.

FIG. 11 illustrates the comparison of cartilage excision results betweena radio-frequency surgical system (RF), an ultrasonic surgical system(US), and a Surgical system using a drill (BUR).

FIG. 12 illustrates a variation example in which an output current isovershot.

FIG. 13 is a block diagram showing a main configuration of theultrasonic surgical system according to the second embodiment of thepresent invention.

FIG. 14 is a flowchart illustrating the treatment using the ultrasonicsurgical system in the third embodiment of the present invention.

FIG. 15 is a diagram to explain the pressure of the excision portion instep S105.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments will be described with reference to thedrawings.

First, the basic principle of the operation of the surgical systemaccording to the present embodiment will be described. The surgicalsystem according to the present embodiment is a surgical system forexcising cartilage. Based on the applicant's analysis, excision ofcartilage is performed in a mechanism different from the excision ofdifferent bone material such as cortical bone and cancellous bone. Thedetails will be described below.

FIG. 1 illustrates components of cartilage, cancellous bone, andcortical bone. As shown in FIG. 1, the main component of the corticalbone and cancellous bone is calcium phosphate, whereas the maincomponent of cartilage is protein (collagen). Collagen is elastic andsoft, unlike calcium phosphate. Accordingly, if an impulse is applied tocollagen, the impulse is absorbed. Because of this characteristic, it isdifficult to excise by applying an impulse cartilage whose maincomponent is collagen.

However, the applicant found out that an ultrasonic surgical system canexcise cartilage. As stated above, cartilage absorbs an impulse. Theultrasonic surgical system excises cartilage by bringing an ultrasonicexcision device (ultrasonic probe) into contact with cartilage, causingthe ultrasonic probe to ultrasonically vibrate in a direction indicatedby an arrow of FIG. 2 to generate friction heat at a position where theultrasonic probe is in contact with cartilage. By the generated frictionheat, cartilage is melted and excised. FIG. 2 illustrates an example ofan ultrasonic surgical system. However, the excision of cartilage byheating may also be performed by using a heating device, instead of theultrasonic surgical system. The excision of cartilage by heating will beexplained in more detail.

FIGS. 3A and 3B illustrate the relationship between the temperature ofcartilage and the amount of excision. FIG. 3A illustrates therelationship between the amount of cartilage excision and thetemperature of cartilage when a soldering iron is pressed onto thecartilage with a predetermined pressure (2.94 N). FIG. 3B illustratesthe relationship between the amount of cartilage excision and thecartilage temperature when an ultrasonic excision device is pressed ontothe cartilage with a predetermined pressure (2.94 N). The horizontalaxes of FIGS. 3A and 3B indicate the temperature (° C.) of the livingtissue (cartilage). The vertical axes of FIGS. 3A and 3B indicate theamount of cartilage excision (mm³). FIG. 4 illustrates the surface andthe cross sectional view of cartilage for each of the temperatures whenthe soldering iron is pressed onto the cartilage. FIG. 4 illustrates thesurface and the cross sectional view of cartilage at 40° C., 80° C.,120° C., 160° C., 200° C., and 240° C.

If the cartilage temperature is lower than 45° C., the cartilage is notexcised as shown in FIGS. 3A and 3B. The surface and the cross sectionalview of cartilage for temperatures lower than 45° C. are shown as thoseat 40° C. in FIG. 4.

If the temperature of cartilage is within the range of 45° C. to 120°C., the amount of cartilage excision becomes greater as the temperaturebecomes higher. The amount of excision does not greatly change accordingto the temperature within the range of 45° C. to 120° C. The surface andthe cross sectional view of cartilage for temperatures within the rangeof 45° C. to 120° C. are shown as those at 80° C. in FIG. 4.

If the cartilage temperature is within the range of 120° C. to 160° C.,the amount of cartilage excision becomes sharply greater as thetemperature becomes higher. The surface and the cross sectional view ofcartilage for temperatures within the range of 210° C. to 160° C. areshown as those at 120° C. in FIG. 4. The cartilage excision progressessignificantly within this range.

If the cartilage temperature is within the range of 160° C. to 200° C.,the amount of cartilage excision increases slightly as the temperaturebecomes higher. The surface and the cross sectional view of cartilagefor temperatures within the range of 160° C. to 200° C. are shown asthose at 160° C. in FIG. 4. If the cartilage temperature becomes 160°C., the cartilage excision progresses, but the surface of cartilagestarts getting burned.

If the temperature of cartilage exceeds 200° C., the burn is expanded,and the amount of excision will be unstable, as shown in FIGS. 3A and3B. The surface and the cross sectional view of cartilage for thetemperature over 200° C. are shown as those at 200° C. and 240° C. inFIG. 4. If the cartilage temperature exceeds 200° C., the surface of theburnt cartilage will be expanded.

As shown in FIG. 3A, cartilage is excised even by applying heat with thesoldering iron. Accordingly, it is understood that cartilage is excisedif heat is applied to cartilage by any means except for the ultrasonicexcision device. However, cartilage is not excised simply by applyingheat if the temperature is lower than 45° C. Thus, it is necessary toheat the cartilage to a temperature of 45° C. or more to excise thecartilage. In addition, if the cartilage temperature exceeds 200° C.,the cartilage is subjected to significant heat insult. Thus, it isdesirable to heat the cartilage to a temperature of 220° C. or less toexcise the cartilage. In consideration of a balance between the amountof cartilage excision and heat insult, it is desirable to heat thecartilage to a temperature of 120° C. to 160° C. to excise thecartilage.

Furthermore, as can be understood from the comparison between FIGS. 3Aand 3B, the amount of cartilage excision for a certain temperature isgreater when using the ultrasonic excision device than when using thesoldering iron. The reason is because the ultrasonic excision device notonly heats the cartilage, but also ablates the melted cartilage away byultrasonic vibration. If the ultrasonic excision device is used forarthroscopic surgery performed in the state where a liquid fills jointcavities, the liquid is stirred by the ultrasonic vibration of theultrasonic excision device. Since the part of the cartilage that hasbeen melted is eliminated by this action, in addition to excision by theultrasonic vibration, a large amount of cartilage can be excised for acertain temperature. That is, if the ultrasonic excision device is usedfor arthroscopic surgery, a larger amount of cartilage can be excised ina short time.

As stated above, when heat is used for excising cartilage, it ispreferable to apply the heat only to a predetermined area to which thetreatment is necessary. For example, if the cartilage to be excised iscartilage of a human body, there is a specific treatment target such asdamaged cartilage or denatured cartilage. Accordingly, it is preferablethat the temperature of only a treatment target such as damagedcartilage or denatured cartilage is increased, and the temperature ofthe peripheral healthy cartilage, subcartilaginous bone, and cancellousbones under the cartilage is not increased. In general, the cellstructure of a human body such as cancellous bones or cortical bones maybe damaged at about 40° C. For the aforementioned cartilage treatment,it is preferable to set the temperature of cartilage to be 120° C. to160° C.

In consideration of the above, it is preferable that the temperature ofthe treatment target, such as damaged cartilage or denatured cartilage,is set as soon as possible to be approximately 120° C., and that thetreatment is then completed before the temperature of healthy tissuearound the treatment target that is not a treatment target, such as acancellous bone, increases. In general, a cancellous bone may be damagedat around 40° C. Accordingly, it is preferable that the temperature ofthe cancellous bone has not been increased to 40° C. when thetemperature of the cartilage or the denatured cartilage becomes 120° C.

FIG. 5A illustrates the increase of the temperature of a cartilage overtime when the ultrasonic excision device in which different outputs areapplied is pressed onto cartilage. The output A in FIG. 5A is an outputadjusted so that the cartilage temperature becomes 120° C. in 2.2seconds. The output B in FIG. 5A is an output adjusted so that thecartilage temperature becomes 120° C. in 2.8 seconds. The output C inFIG. 5A is an output adjusted so that the cartilage temperature becomes120° C. in approximately 20 seconds. On the other hand, FIG. 5Billustrates the increase of the temperature of a subcartilaginous boneover time when the ultrasonic excision device is pressed onto cartilagewith outputs A, B, and C of FIG. 5A. For the output A with which thetemperature of cartilage becomes 120° C. in 2.2 seconds, the temperatureof the subcartilaginous bone does not exceed 40° C. when the temperatureof cartilage becomes 120° C. On the other hand, for the output B withwhich the temperature of cartilage becomes 120° C. in 2.8 seconds, thetemperature of the subcartilaginous bone exceeds 40° C. before thetemperature of cartilage becomes 120° C., as shown in FIG. 5B.Similarly, for the output C with which the temperature of cartilagebecomes 120° C. in 20 seconds, the temperature of the subcartilaginousbone exceeds 40° C. before the temperature of cartilage becomes 120° C.,as shown in FIG. 5B.

FIG. 6A is a schematic diagram of a temperature distribution ofcartilage and cancellous bone when the temperature of the cartilage is120° C. at output A. As shown in FIG. 6A, when the operation isperformed for 2.2 seconds, only the temperature of cartilage becomeshigh, and the increase of the temperature of subcartilaginous bone andcancellous bone around the cartilage can be suppressed. FIG. 6B is aschematic diagram of temperature distribution of cartilage, andcancellous bone when the temperature of the cartilage is 120° C. atoutput B. As shown in FIG. 6B, when the operation is performed for 2.8seconds, heat transmitted to cartilage is transmitted to thesubcartilaginous bone and the cancellous bone, and the temperature ofthe cancellous bone exceeds 40° C. FIG. 6C is a schematic diagram of atemperature distribution of cartilage and cancellous bone when thetemperature of the cartilage is 120° C. at output C. In the exampleshown in FIG. 6C, the temperature of the subcartilaginous bone and thecancellous bone exceeds 0° C. before the temperature of cartilagesufficiently increases.

As can be seen from above, it is desirable that the operation of theultrasonic excision device is performed within 2.2 seconds. That is, thesurgical system suitable for treating human cartilage can be realized byadjusting the output, etc. so that the temperature of cartilage becomes120° C. within 2.2 seconds.

First Embodiment

The first embodiment is explained below. FIG. 7 illustrates an exampleof a detailed configuration of the surgical system according to theembodiments of the present invention. As stated above, excision ofcartilage is performed by heating the cartilage to a suitabletemperature. Any means for heating the cartilage to a suitabletemperature can be used. For example, the surgical system of the presentembodiment may adopt a system that heats cartilage to a temperature of45° C. to 220° C., preferably, 120° C. to 160° C., by friction heat viaultrasonic vibration; a system that heats cartilage to a temperature of45° C. to 220° C., preferably 120° C. to 160° C., by a hearer; or asystem that heats cartilage to a temperature of 45° C. to 220° C.,preferably 120° C. to 160° C., by applying a radio frequency current.FIG. 7 illustrates an ultrasonic surgical system 1 as an example of thesurgical system according to the present embodiment.

The ultrasonic surgical system 1 shown in FIG. 7 includes an excisiondevice 10 that treats a living tissue by ultrasonic waves, a powersupply device 80 that supplies driving power to the excision device 10,and a foot switch 90. The ultrasonic surgical system 1 is suitable fortreating cartilage. However, the ultrasonic surgical system 1 may beused for treating a living tissue other than cartilage.

The excision device 10 functioning as an energy excision device includesa hand piece 20, a probe 180 protruding from the hand piece 20, and aslender-shaped sheath 30 formed around the probe 180. In theexplanations below, the side of the excision device 10 where the probe180 is provided is called a distal end, and the side of the excisiondevice 10 where the hand piece 20 is provided is called a proximal end.

The hand piece 20 includes an ultrasonic transducer therein. Theultrasonic transducer ultrasonic vibrates in accordance with the drivingpower from the power supply device 80. The hand piece 20 transmits theultrasonic vibration generated at the ultrasonic transducer to the probe180. The probe 180 is connected to the ultrasonic transducer, andvibrates according to the vibration of the ultrasonic transducer.

The distal end of the sheath 30 has a semi-cylindrical shape, and theexcision portion 181 provided at the distal end of the probe 180 isexposed from the semi-cylindrical portion. The distal end of the sheath30 is provided with a cold knife 182, for example. The cold knife 182 isformed of a corrosion-resistant metallic material, and is used tofacilitate excision of a living tissue. The cold knife 182 may beomitted.

The hand piece 20 includes an input unit 22. The input unit 22 is toinput an instruction for driving the ultrasonic transducer. The inputunit 22 may include a plurality of switches so that the driving of aplurality of types of ultrasonic transducers may be carried outaccording to a plurality of types of inputs. The plurality of switchesincludes a switch to drive the ultrasonic transducer suitable fortreatment of the cartilage. The input unit 22 is connected to the powersupply device 80. The ultrasonic transducer within the hand piece 20 isconnected to the power supply device 80. The power supply device 80detects an input to the input unit 22, and supplies driving power to theultrasonic transducer in accordance with the detected input.

The foot switch 90 has a function similar to that of the input unit 22provided to the hand piece 20. That is, the foot switch 90 includes aswitch similar to the input unit 22. The foot switch 90 may include aplurality of switches, similar to the input unit 22. If the power supplydevice 80 detects an input to the foot switch 90, the power supplydevice 80 supplies a driving electric power to the ultrasonic transducerin accordance with the detected input. At least one of the input unit 22and foot switch 90 may be provided.

When performing treatment, a user holds the hand piece 20 and brings theexcision portion 181 provided in the probe 180 that is ultrasonicallyvibrating into contact with a living tissue that is a treatment object.The user operates the input unit 22 or the foot switch 90 to vibrate theultrasonic transducer at this time. The vibration generated at theultrasonic transducer is transmitted to the probe 180. The living tissueis cut or excised by bringing the excision portion 181 of the probe 180that is vibrating into contact with the living tissue.

FIG. 8 is a block diagram illustrating the main configuration of theultrasonic surgical system 1 according to the first embodiment of thepresent invention. In FIG. 8, the same structures as explained withreference to FIG. 7 are indicated with the same reference numerals, andthe explanations thereof will be omitted.

As shown in FIG. 8, the power supply device 80 includes an outputcircuit 81 and a control circuit 82.

The output circuit 81 is electrically connected to an ultrasonictransducer 24, and generates driving power to drive the ultrasonictransducer 24 provided inside of the hand piece 20 of the excisiondevice 10. Based on the driving power, an output voltage and an outputcurrent are output from the output circuit 81 to the excision device 10.

The control circuit 82 is configured by an ASIC including a CPU, forexample, and controls the driving power of the output circuit 81 inaccordance with an input from the input unit 22 or the foot switch 90.For example, if an instruction to enter the cartilage excision mode ismade by the input from the input unit 22 or the foot switch 90, thecontrol circuit 82 controls the output circuit 81 to allow theultrasonic vibration to be generated at the excision device 10 toincrease the temperature of cartilage to the aforementioned temperature,namely 45° C. to 220° C., preferably to 120° C. to 160° C. For theultrasonic surgical system, the cartilage temperature changes inaccordance with the friction heat. Based on the applicant's analysis, itis understood that the heating amount by friction heat is determinedbased on the amplitude of the ultrasonic vibration and the pressure whenpressing the excision device 10 to the cartilage, as shown FIG. 9. Thus,if the pressure is fixed the average value of the pressure when a doctorpresses the excision device 10 onto a living tissue, the friction heatonly changes by the amplitude. In the present embodiment, amplitudewhere cartilage is heated to 45° C. to 220° C., preferably to 120° C. to160° C., is measured in experiments with the fixed pressure, and themeasured amplitude values are stored in a memory 821 of the controlcircuit 82. The control circuit 82 reads the amplitude value from thememory 821, and controls the output current and the output voltage ofthe output circuit 81 so that the ultrasonic transducer 24 vibrates withthe read amplitude value.

In addition, as stated above, it is preferable that the temperature ofthe treatment target is increased to 120° C. in approximately 2.2seconds. If the amplitude of ultrasonic vibration is simply increased,it is possible to increase the temperature of the treatment target for ashort time in the ultrasonic surgical system. Furthermore, it ispossible to increase the temperature of the treatment target in ashorter time by increasing the pressure applied to the excision portion.

The operation of the ultrasonic surgical system 1 of the presentembodiment will be explained below. FIG. 10 is a flowchart illustratingthe treatment using the ultrasonic surgical system 1 in the firstembodiment. The treatment shown in FIG. 10 is the excision ofdegenerated cartilage at a knee joint. The treatment flow shown in FIG.10 is not limited to a knee joint, but may be applied to other jointssuch as a shoulder joint.

In step S101, a doctor uses a trocar to form a port through which anexcision device and an arthroscope can be inserted into a position of aliving tissue to be treated (in this case, degenerated cartilage at aknee joint).

In step S102, the doctor inserts the arthroscope and the excision device10 of the ultrasonic surgical system 1 into the knee joint through theport for the arthroscope.

In step S103, the doctor brings the excision portion 181 of theultrasonic surgical system 1 into contact with the degenerated cartilageto be treated while watching an image of the knee joint displayed or amonitor through the arthroscope.

In step S104, the doctor, for example, operates the input unit 22 setsthe ultrasonic surgical system 1 to the cartilage mode, and startsexcision of the degenerate cartilage. If the ultrasonic surgical system1 is set to the cartilage mode, the control circuit 82 reads theamplitude value pre-stored in the memory 821 (for example, the amplitudevalue required to heat the cartilage to 120° C.), and controls theoutput circuit 81 so that the ultrasonic transducer 24 vibrates at theread amplitude. By bringing the excision portion 181 vibrating at theread amplitude into contact with the denatured cartilage with a fixedpressure, the temperature of the degenerated cartilage becomes about120° C. The degenerated cartilage is then melted, and excised. The valueof amplitude in step S104 is preferably a value required to increase thetemperature of cartilage to 120° C. in a predetermined short time(within 2.2 seconds). By this process, the treatment is completed in ashort time, and an unnecessary increase in the temperature of anon-treatment target is prevented.

In accordance with the aforementioned embodiment, the amount ofcartilage heating by the excision device 10 is controlled to heat thecartilage to a temperature of 45° C., by paying attention to the factthat the cartilage heated to 45° C. or higher is melted and excised. Bythis procedure, cartilage can be reliably excised.

In addition, according to the present embodiment, the heating amount ofthe cartilage by the excision device 10 is controlled to heat thecartilage to be within the predetermined range of 45° C. to 220° C.,preferably within 120° C. to 160° C., in consideration of heat insult tothe cartilage. By this procedure, cartilage can be excised with a smallamount of heat insult.

Furthermore, according to the present embodiment, the treatment can becompleted in a short time by treating cartilage by the excision portion10. Accordingly, an unnecessary increase in the temperature of anon-treatment target that does not need treatment is prevented.

In the aforementioned embodiment, the ultrasonic surgical system isillustrated as a surgical system. In the present embodiment, it ispossible to apply a surgical system using a heater, a surgical systemusing a radio frequency current, or a combination thereof using energydifferent from ultrasonic waves, other than the ultrasonic surgicalsystem if the cartilage can be heated to the predetermined range of 45°C. to 220° C. preferably to 120° C. to 160° C. However, the ultrasonicsurgical system can reduce the amount of heat insult in comparison withthe surgical system using a heater or a radio frequency. In addition,the ultrasonic surgical system can excise the cartilage to make theexcised surface smooth in comparison with the surgical system using aheater or radio frequency. Furthermore, the ultrasonic surgical systemcan excise a larger amount of cartilage in comparison with the surgicalsystem using a motor.

FIG. 11 illustrates the comparison of cartilage excision results betweena radio-frequency surgical system (RF) and an ultrasonic surgical system(US). FIG. 11 also includes the cartilage excision results of a surgicalsystem using a drill (BUR) (i.e., results of impulse-only excision) forcomparison. As shown in FIG. 11, the cartilage is hardly excised by theimpulse-only excision treatment. Rather, the cartilage surface becomesvillus-like shaped, without retaining its original shape. On the otherhand, with the excision treatment using radio frequency, the amount ofexcision is larger than the treatment using a drill; however, the amountof heat insult is relatively extensive. In comparison with the above,with the excision treatment using ultrasonic waves, greater progress ismade in cartilage excision, while relatively suppressing the amount ofheat insult.

It is known that the speed of an increase in heat is slower when usingthe ultrasonic surgical system than when using the radio-frequencysurgical system. Thus, it is possible to overshoot the output current incomparison with the output current corresponding to the desiredamplitude only during a predetermined period of time immediately afterstarting the ultrasonic surgical system, as shown in FIG. 12, so thatthe temperature of the cartilage reaches the target temperature faster.

Second Embodiment

The variation example of the embodiment will be explained below. In theaforementioned embodiment, the amount of cartilage heating by theexcision device 10, to heat the cartilage to the temperature suitablefor excision, is controlled in accordance with a setting (for example,amplitude) predetermined by actual measurements. In the secondembodiment, the amount of cartilage heating by the excision device 10 isfeedback controlled.

FIG. 13 is a block diagram illustrating the main configuration of theultrasonic surgical system 1 according to the second embodiment of thepresent invention. In FIG. 13, the same structures as explained withreference to FIG. 8 are indicated with the same reference numerals, andthe explanations thereof will be omitted.

The excision device 10 of the ultrasonic surgical system 1 according tothe second embodiment includes a temperature sensor 26. The temperaturesensor 26 is provided within the distal end of the excision device 10,for example, detects the temperature of the distal end of the excisiondevice 10, i.e., the temperature of cartilage, and inputs a signalaccording to the detected temperature to the control circuit 82 of thepower supply device 80. Various temperature sensors such as athermocouple and a thermistor may be used as the temperature sensor 26.

The control circuit 82 according to the second embodiment controls theoutput circuit 81 to maintain the temperature measured by thetemperature sensor 26 at a predetermined temperature within the range of45° C. to 220° C., preferably within 120° C. to 160° C. For example, thecontrol circuit 82 controls the output circuit 81 to increase the outputcurrent from the output circuit 81 if the temperature measured by thetemperature sensor 26 is below the predetermined temperature. Inaddition, the control circuit 82 controls the output circuit 81 todecrease the output current from the output circuit 81 if thetemperature measured by the temperature sensor 26 exceeds thepredetermined temperature.

According to the aforementioned second embodiment, cartilage is morereliably excised by performing feedback control to the output power fromthe output circuit 81 in accordance with the cartilage temperaturemeasured by the temperature sensor, in comparison with the firstembodiment. In the second embodiment, it is possible to omit the memory821 applied in the first embodiment.

In the second embodiment, the temperature of the cartilage is measuredby the temperature sensor 26. However, the cartilage temperature is notlimited to being measured by the temperature sensor.

Third Embodiment

The third embodiment is explained below. The third embodiment is avariation example of the treatment method. As described above, it ispreferable that the temperature of only the treatment target isincreased to 120° C. to 160° C. during the treatment, and thetemperature of non-treatment target is below 40° C. With this purpose,the amplitude may be increased, or the pressure may be increased in theultrasonic surgical system 1. The present embodiment accomplishes ashorter treatment by a particular treatment method.

FIG. 14 is a flowchart illustrating the treatment using the ultrasonicsurgical system in the third embodiment. Similar to FIG. 10, thetreatment shown in FIG. 14 is the excision of denatured cartilage at aknee joint. The treatment flow shown in FIG. 14 is not limited to a kneejoint, but may be applied to other joints such as a shoulder joint. InFIG. 14, the explanations of the same structures as explained withreference to FIG. 10 will be omitted. That is, the processes at stepsS101 to S103 will be omitted.

In step S204, the doctor, for example, operates the input unit 22 to setthe ultrasonic surgical system 1 to the cartilage mode, and startsexcision of the denatured cartilage. If the ultrasonic surgical system 1is set to the cartilage mode, the control circuit 82 reads the amplitudevalue pre-stored in the memory 821 (for example, the amplitude valuerequired to heat the cartilage to 120° C. within 2.2 seconds), andcontrols the output circuit 81 so that the ultrasonic transducer 24vibrates at the read amplitude. By bringing the excision unit 181vibrating at the read amplitude into contact with the denaturedcartilage with a fixed pressure, the temperature of the denaturedcartilage increases.

In step S205, the doctor excises (energy-assisted trims, removes, oraccurately shaves) cartilage by the probe 180, as shown in FIG. 15. Theprocess shown in FIG. 15 indicates excising (paring) cartilage bygenerating continuous amount of film-shaped shavings as in peeling awayskin. Specifically, the doctor presses the excision unit 181 in thedirection substantially parallel to the surface of cartilage, which isdifferent from the direction of contact. By this process, a compressiveforce is applied to the cartilage, and the temperature of the cartilageincreases further. The denatured cartilage is then melted and excised.In addition, by applying pressure to the excision unit 181 in thedirection substantially parallel to the surface of the heated cartilage,the surface of the cartilage is shaved as a film, as shown in FIG. 15.Accordingly, the denatured cartilage is excised more efficiently.

According to the aforementioned embodiment, a more efficient excision ofthe denatured cartilage is realized by applying the pressure to theexcision unit 181 in the direction substantially parallel to the surfaceof heated cartilage, in addition to the advantageous effects explainedin the first embodiment. In step S205, the direction of pressing isdifferent from the direction of contact. However, it may be possible toexcise in the thickness (depth) direction of cartilage by pressing inthe direction of contact.

The process at step S205 of the third embodiment can be applied to asurgical system using a heater, a surgical system using a high frequencycurrent, or a combination thereof using energy different from ultrasonicwaves, other than the ultrasonic surgical system.

The embodiments have been described, but the present invention is in noway limited to these embodiments. The present invention can, of course,be modified in various ways without departing from the spirit and scopeof the invention.

What is claimed is:
 1. A method for treating cartilage of a human beingby melting the cartilage by friction heat, the method comprising:bringing an excision unit into contact with a predetermined portion ofthe cartilage; melting the cartilage by heating the predeterminedportion of the cartilage to a temperature of 120° C. or higher by theexcision unit within 2.2 seconds; and excising, by the excision unit,the predetermined portion of the cartilage that has been heated to thetemperature of 120° C. or higher while pressing the predeterminedportion.
 2. The method for treating cartilage according to claim 1,wherein the predetermined portion is pressed in a direction differentfrom a direction that the excision unit is in contact with thecartilage.
 3. The method for treating cartilage according to claim 1,wherein the predetermined portion of the cartilage is damaged cartilageor denatured cartilage.
 4. The method for treating cartilage accordingto claim 1, further comprising: preventing a temperature of asubcartilaginous bone and a cancellous bone other than the predeterminedportion of the cartilage from exceeding 40° C.
 5. The method fortreating cartilage according to claim 1, wherein the melting of thecartilage includes generating the friction heat to heat the cartilagenot to exceed 220° C.
 6. The method for treating cartilage according toclaim 1, wherein the melting of the cartilage includes generating thefriction heat to heat the cartilage not to exceed 160° C.
 7. The methodfor treating cartilage according to claim 1, wherein the excising of thepredetermined portion includes generating a continuous amount offile-shaped shavings.
 8. The method for treating cartilage according toclaim 1, wherein the excision unit is an ultrasonic probe.
 9. The methodfor treating cartilage according to claim 1, wherein the excision unitis a heating device.